Assistive devices, such as walking sticks, canes, crutches, walkers and the like, are important means for assisting the aged, patients with leg problem, the disabled and climbers, hereinafter generally referred to as the user, in standing and walking stably and safely. The assistive devices are mainly used to provide the user with a support and form a supporting point to reduce the load of the user's legs. Conventionally, according to different manners of use, the assistive devices are generally classified into some different types, such as walking sticks gripped by a user with one hand and underarm crutches held between the user's armpit and ribcage. The walking stick includes a handle provided on a top thereof, and the user grips at the handle when standing or walking with the aid of the walling stick, so that force applied by the user against the handle is transmitted to the ground. The underarm crutch includes a curved pad provided on a top thereof for pressing against the user's armpit, and the user clamps the curved pad between the armpit and the ribcage while grips at a handgrip when standing or walking with the aid of the crutch, so that force applied by the user against the handgrip can be transmitted to the ground.
The conventional assistive devices, such as the walking sticks and the underarm crutches, can have a single-point or a four-point lower end. When the assistive device touches the ground, there is produced a ground reaction force. To reduce the impact of the ground reaction force on the user and to prevent the assistive device from skidding, a rubber ferrule is usually fitted onto the lower end of the assistive device. The rubber ferrule generally has a truncated conical shape or a barrel shape and provides a degree of elasticity. The elasticity of the rubber ferrule buffers the ground reaction force when the assistive device touches the ground, making the assistive device more comfortable and safer for use. Meanwhile, the rubber ferrule increases a frictional force between the lower end of the assistive device and the ground surface to thereby provide an anti-skidding effect.
The single-point assistive device has the advantages of small in volume and convenient to handle, but it provides only one supporting point when the user walks and the single-point lower end of the assistive device touches the ground. With the help of the only one supporting point, the user shifts his or her body gravity center during moving. In the course of shifting the body gravity center, the user handles the assistive device to touch the ground surface, and uses the ground-touching point as a supporting point to shift the body. The rubber ferrule has a thickness and a configuration that can only provide the assistive device with very limited swinging span and buffering effect. As a result, the assistive device just could not be smoothly and conveniently handled by the user. Further, the rubber ferrule is subject to elastic fatigue and wearing after frequent use over a long time, and therefore requires checking and replacement now and then.
On the other hand, the four-point assistive device provides four supporting points, and is therefore more stable and easier for use, compared to the single-point assistive device. A problem in using the four-point assistive device is that the user can exert force and shift his or her body gravity center only when all the four points of the lower end of the assistive device touch the ground surface, lest the user should lose balance and fall down. Further, the four-point assistive device does not swing forward and backward when the user exert force to shift the body gravity center, and is therefore not so convenient for handle in a smooth way.